Optical sources such as laser diodes are commonly used for communication links over fiberoptic cables. The alignment of the fiberoptic thread-like transmission medium to a laser diode for the efficient transfer of optical power requires accurate positioning and alignment fixtures. The process is even more complex when an array of several sources and optical fibers are involved.
One of the prior art techniques has been to utilize silicon substrates and to etch, utilizing photolithographic alignment techniques, grooves in the substrate in order to accurately locate the optical fibers in relation to edge-emitting laser diodes.
Since testing of edge-emitting laser diodes prior to assembly is unreliable, it is not uncommon for arrays to be assembled only to find that the lasers do not meet wavelength or power output requirements. This results in low assembly yields which in turn increases the module costs.
Recent developments in surface-emitting laser diode technology has meant that more traditional and well-proven processing techniques can be utilized in the fabrication of laser arrays. This has resulted in devices having metalization configurations applicable to flip-chip bonding, thereby eliminating assembly problems associated with wire bonding.